The present invention relates to seat track assemblies, and more particularly, to apparatuses for positive engagement of seat tracks and loading thereof.
Seat track assemblies are common within automotive vehicles for displacement of seat assemblies in fore and aft directions. Seat track assemblies typically include a pair of parallely spaced track assemblies; each track assembly includes an upper track that resides in translational relationship with a lower track. The lower track is rigidly fixed to a vehicle structure whereas the upper track is coupled to a seat pan and is able to be translated in relation to the lower track.
The seat track assemblies include a latching mechanism, which is commonly coupled to the upper track and is used to secure the upper track to the lower track. The latch mechanism, for example, may include a bracket with a series of teeth that are rigidly coupled to the upper track and which engage with a series of apertures in the lower bracket. To adjust position of the seat assembly a release lever is operated to release or disengage the pins from the apertures. Once in an approximately desired position the release lever again is operated or released into an engaged position to engage the pins and lock the upper track to the lower track.
It is desirable for a latching mechanism to provide positive continuous engagement, hereinafter referred to as positive engagement. Positive engagement describes the situation when the release lever is actuated and the latch mechanism returns to a locked state or an engaged state without physically adjusting position of the upper track in relation to the lower track.
Several positive engagement seat track latching mechanisms currently exist. Each positive engagement mechanism typically, has a series of spring-loaded pawls or pins that are coupled to an upper track and independently engage with a series of apertures in a lower track. When a corresponding release lever is operated one or more of the pins engage with the apertures. The apertures are rectangular in shape and have a length in the fore and aft direction that is significantly larger than that of width of the pins and a distance between apertures that is approximately equal to width of the pins, such that at least one pin always is engaged when the release lever is in an engaged position.
It is also desirable to provide desired loading resilience, which often corresponds with having at least two pins engaged at all times. With current positive engagement mechanisms a situation exists when a single pin is engaged and is within a center position of an aperture, such that other remaining pins are not engaged. When in this situation, in order to engage a second pin the upper track needs to be physically adjusted in relation to the lower track to engage a second pin and rigidly fix the upper track member to the lower track member. Amount of displacement required by the upper track in relation to the lower track to engage the second pin is referred to as resolution.
It is further desirable for a seat latching mechanism to have minimum resolution. The lower the resolution the better the perceived impression by a seat operator of a seat assembly having infinite adjustability. Unfortunately, resolution of existing seat track assemblies is high, such that the upper track may need to be adjusted as much as 6 mm to engage a second pin.
Also, current positive engagement seat track assemblies do not provide additional or aid in maintaining engagement of the pins during a vehicle collision. During a vehicle collision, due to vertical load on a seat assembly, gap between an upper seat track and a lower seat track may increase causing one or more pins to disengage, thereby, releasing the upper track in relation to the lower track.
It is therefore desirable to provide a positive engagement seat track assembly that has minimal resolution, has features for maintaining engagement of seat tracks, is cost effective, and provides manufacturing ease.